Effect of letrozole on masculinization of Siamese fighting fish (Betta splendens)

The aim of this study was to evaluate the effect of letrozole (a non-steroidal aromatase inhibitor) on masculinization of Siamese fighting fish (Betta splendens). Different doses of letrozole 50, 100, 150 and 200 ppm (mg/kg feed) were incorporated into diet and fed for periods of 30, 40 or 50 days. Immersion treatment of letrozole at selected doses (250, 500, 750 and 1,000?g/l) for 3 h each on third, fifth and eighth day-post-hatching (dph) (Trial 1) and fourth, sixth and eighth dph (Trial 2) was given.The oral administration of letrozole for 30, 40 or 50 days did not have any significant effect on the sex ratio of B. splendens. The immersion treatment of letrozole induced 100% masculinization at 500 and 1000?g/l in trial 1, while it yielded only 66.66 and 90% male population at 500 and 1000 ?g/l in Trial 2. The dietary administration of letrozole for 30 and 50 days caused tail deformities and/or rudimentary and absence of dorsal fin. The progeny testing of males from letrozole treated (both oral and immersion) groups indicate that the sex ratio of progenies of each of the males tested did not differ significantly from that of control, indicating that all those males carried XY genotype. Letrozole treatments suppressed ovarian development (atretic oocytes were common). However, the testicular development was unaffected. The study revealed that immersion treatment of letrozole was more effective in inducing masculinization of B. splendens than the oral administration of letrozole

Effect of anastrozole on masculinization in ornamental fish, dwarf gourami, <i>Trichogaster lalius</i> (Hamilton, 1822)

581-589In ornamental fishery, for commercialization and efficient propagation of fish species in demand, controlling their sex, male or female, plays an important role as it influences reproduction, growth and product quality. In one such common aquarium fish, dwarf gourami, Trichogaster lalius (Hamilton, 1822), males look more attractive and fetch better market price encouraging masculinization of this species. In the present study, we evaluated the effect of anastrozole on masculinization potential in T. lalius. The experiment consisted of two trials, in trial 1; anastrozole was incorporated into feed at 50, 100, 150 and 200 mg/kg and fed to first feeding fry for 50 days. In trial 2, immersion treatment of anastrozole was carried out at different doses of 250, 500, 750 and 1,000 μg/L for 3 h each on 3rd, 5th and 8th day of post-hatching. Oral administration of anastrozole resulted in 90.32% masculinization at 200 ppm and the immersion treatment of anastrozole produced 100% masculinization at 1000 μg/L. Histological sections indicated that the anastrozole treatments suppressed ovarian development, leading to the atretic oocytes. However, the testicular development was unaffected. Testosterone level increased whereas estradiol level decreased with increased dose of the chemical. Cortisol level also showed a significant increase in male with increased doses of anastrozole, indicating stress which in turn helped to synthesize the testosterone. The results show that the immersion treatment of anastrozole is more effective than oral administration in inducing masculinization in T. lalius.</i

Effect of anastrozole on masculinization in ornamental fish, dwarf gourami, Trichogaster lalius (Hamilton, 1822)

In ornamental fishery, for commercialization and efficient propagation of fish species in demand, controlling their sex, male or female, plays an important role as it influences reproduction, growth and product quality. In one such common aquarium fish, dwarf gourami, Trichogaster lalius (Hamilton, 1822), males look more attractive and fetch better market price encouraging masculinization of this species. In the present study, we evaluated the effect of anastrozole on masculinization potential in T. lalius. The experiment consisted of two trials, in trial 1; anastrozole was incorporated into feed at 50, 100, 150 and 200 mg/kg and fed to first feeding fry for 50 days. In trial 2, immersion treatment of anastrozole was carried out at different doses of 250, 500, 750 and 1,000 μg/L for 3 h each on 3rd, 5th and 8th day of post-hatching. Oral administration of anastrozole resulted in 90.32% masculinization at 200 ppm and the immersion treatment of anastrozole produced 100% masculinization at 1000 μg/L. Histological sections indicated that the anastrozole treatments suppressed ovarian development, leading to the atretic oocytes. However, the testicular development was unaffected. Testosterone level increased whereas estradiol level decreased with increased dose of the chemical. Cortisol level also showed a significant increase in male with increased doses of anastrozole, indicating stress which in turn helped to synthesize the testosterone. The results show that the immersion treatment of anastrozole is more effective than oral administration in inducing masculinization in T. lalius

Significance of water pH and hardness on fish biological processes: A review

The success of any aquaculture endeavour broadly depends on water quality. Water quality determines to a great extent the success or failure of aquaculture operation. Optimum water quality is considered necessary for any aquaculture operation as it influences the productivity of production system. In the present review, the role of major abiotic factors such as water pH and hardness on the biological processes of fish like growth, survival, reproductive performance and embryology has been discussed

Embryonic Development of Discus, Symphysodon aequifasciatus Pellegrin, 1904 in Indian Condition

The experiment was conducted to investigate the embryonic development of discus (Symphysodon aequifasiatus) and determine the time required for major egg developmental stages and hatching. Regular observations were made using optical microscope and the images were recorded using a digital camera attached to the microscope. Important water quality parameters were kept optimal for the hatching of discus eggs. Newly laid eggs were oval-shaped and yellow in colour with an average diameter of 1.37 ± 0.14 mm. The embryonic development of fertilized eggs was divided into 16 stages and the development of each stage was recorded in times lapse. The result revealed that cleavage occurred after 1hr after fertilization followed by development of blastula and gastrula at 20.5 hr and 24 hr after fertilization respectively. The period of organogenesis started with the formation of embryonic notochord from 37.5 hrs after fertilization. The appearance of a defined head and tail of the embryo with 19 somites was observed at 40.0 hrs after fertilization, whereas heart beat along with blood circulation appeared after 55.5 hrs after fertilization. The eggs hatched after 69.06 hr after fertilization

Fernando Ortiz y las relaciones científicas hispano-cubanas, 1900-1940

La formación científica que Fernando Ortiz adquirió en España junto a prestigiosos hombres de la cultura –antropología, criminología, sociología e historia–, su concepción de la cultura, la ciencia, la nación y el contacto continuo con muchos de los intelectuales herederos de los principios de la Institución Libre de Enseñanza y miembros de la Junta para la Ampliación de Estudios e Investigaciones Científicas, fueron elementos claves para el establecimiento de las relaciones culturales y científicas entre España y Cuba, basadas en la ciencia. La consolidación de éstas, con la creación de la Institución Hispanocubana de Cultura, posibilitó la acogida de exiliados intelectuales españoles en 1939.Peer reviewe